A known tennis racquet is disclosed in U.S. Pat. No. 4,194,738. The hollow section with U-shaped profile shown therein is not provided with reinforcement ribs in the inner space. The reinforcement ribs are instead formed on the middle bridge of the counter-section inserted in the hollow section and supported on the base of the connecting bridge of the hollow section with U-shaped profile. The object of this expedient is the transmission of the forces generated during stringing onto the hollow section. A disadvantage of this known racquet is that the reinforcement ribs formed as concentric, circulating ribs on the counter-section act such that the racquet head is only slightly stable with respect to distortion, because the concentric, continuous rib loosely adjoining the inner surface of the connecting bridge of the hollow section allows relatively large twisting of the racquet head. A further disadvantage is that a small bending resistance and a poor damping property are obtained.
Moreover, the known tennis racquets suffer from detrimental weight distribution because they are considerably top heavy. The hollow section of U-shaped profile is constructed with the same thickness over the entire racquet head, which leads to the top of the tennis racquet being especially heavy, causing the above-described top-heaviness and impeded play.
The hollow section of U-shaped profile arranged in the area of the racquet head converges in a double-T profile in the area of the handle. Injection molding technology can produce such a double-T profile only if corresponding lateral sliders are used, which leads to increased manufacturing expenditures and therefore a higher cost for these tennis racquets. Moreover, a disadvantage encountered is that handles with only one and the same thickness can be produced in the mold. Also, it is not possible to employ replaceable inserts by means of which handles of different thicknesses can be produced. Different handle thicknesses can be achieved in this known tennis racquet only by molding a multi-sided handle section on the double-T section, which is again encircled by a corresponding cover strip. This gives rise to the disadvantage that the handle is made of different materials, thereby raising the possibility of joinder problems.
In French Patent No. 2270908 another tennis racquet frame made by injection molding techniques is disclosed. This frame comprises two assembled half shells which are superimposed to grip each other in an overlapping manner and are connected to each other. The profile of this tennis racquet does not comprise an outwardly open hollow section of U-shaped profile, resulting in the disadvantage of poor bending resistance, poor warping resistance, and poor damping action.